Competitive game apparatus including groups of electric switches

ABSTRACT

As a competitive game, there is provided a casing having opposite faces on which are arranged respective matrices of switches. The switches of each matrix are connected to each other via switches of the other matrix. Proper operation of switches in both matrices can result in the formation of a continuous circuit along a coordinate of one of the matrices at any given time. A power source and respective indicators show which group includes such continuous circuit. The continuous circuit can be opened by operation of a switch in the other matrix. A clock is used to show the cumulative advantage which one matrix has over the other. Additional matrices can be connected to the basic matrices.

United States Patent [191 Secter 1 1 Dec. 18, 1973 1 COMPETITIVE GAME APPARATUS INCLUDING GROUPS OF ELECTRIC SWITCHES [76] Inventor: Michael Secter, 305 Canal St., New

' York, NY. 10013 [22] Fi1ed: Mar. 2, I972 [21] Appl. No.: 231,338

[52] US. Cl. 273/130. AB, 273/1 E [51] [58] Field of Search, 273/1 E, 130 AB -[56] References Cited UNITED STATES PATENTS 3,404,889 10/1968 warner .Q 273/130 AB 3,226,121 12/1965 Go1dfarb.... 273/86 B 3,690,665 9/1972 Becker 273/130 AB 3,367,653 2/1968 Brown... 273/1 E 2,799,505 7/1957 Lyons 273/1 E 3,420,526 1/1969 Berger 273/148 R Primary Examiner-Anton O. Oechsle Alt0rneyA1an K. Roberts et a1.

57 ABSTRACT I As a competitive game, there is provided a casing having opposite faces on which are arranged respective matrices of switches. The switches of each matrix are connected to each other via switches of the other matrix. Proper operation of switchesin both matrices can result in the formation of a continuous circuit along a coordinate of one of the matrices at any given time. A

power source and respective indicators show which group includes such continuous circuit. The continuous circuit can be opened by operation of a switch in the other matrix. A clock is used to show the cumu1ative advantage which one matrix has over the other.

Additional matrices can be connected to the basic matrices.

16 Claims, 4 Drawing Figures SHEET 10? 3 PAIENIEDUEE 18 I915 PATENTEDHEB 18 ms SHEET 30? 3 FIG-3 FIELD OF THE INVENTION This invention relates to competitive game apparatus and more particularly to' competitive game apparatus of the type wherein groups of switches are employed in a tactical sense to out-manuever an opponent.

SUMMARY or THE INVENTION It is an object of the invention to provide an improved and novel competitive game apparatus.

It is another object of the invention to provide an improved game apparatus suitable for testing intellectual skills as well as skills relating to manual dexterity.

It is yet a further object of the invention to provide an improved game apparatus suitable for use by two or more contestants.

A further object of the invention is to provide an improved game apparatus having appeal to a wide variety of contestants and age groups.

Still another object of the invention is to provide an improved game apparatus which is readily employed by contestants while providing an extraordinary amount of excitement.

Still another object of the invention is to provide an improved game apparatus, the rules for which are easily understood and readily employed without detracting from the degree of skill which is required.

In achieving the above and other objects of the invention, there is provided an apparatus which comprises first and second groups of switches, the switches of each group being interconnected through the switches of the other group and being adapted for-forming at least one continuous electrical-circuit in each group, there being furthermore provided a power source connected to each group and indicating means to indicate when 'a continuous circuit is formed.

In using apparatus of the above-noted type, each contestant associates himself with one of the groups of switches and freely operates the same in an attempt to form a continuous circuit within his own group. This forming of a continuous circuit is, however, controlled at least in part by the other contestant who is operating switches to form his own continuous circuit and while doing so is interfering with the setting up of a continuous circuit in his opponents group because of the interconnection between the switches of the different groups.

In the aforesaid arrangement, each switch will preferably include an operating member and the operating members of each group will be physically juxtaposed and spaced from the operating members of the other group.

According to a feature of the invention, the aforesaid indicating means includes'an indicator for each respective group. These indicators may, for example, be lamps; however, they may alternatively be alarms, such as bells or the like.

In accordance with another feature of the invention, the indicating means may include, in addition to the indicators or alternatively thereto, a means for storing the total cumulative time differential between the periods that continuous circuits are formed in the respective groups. In this case, the object of the use of the game apparatus of the invention will be to gain a cumulative time advantage over an opponent by amassing a total of time during which continuous circuits are formed in a specific group.

'In the event that a total cumulative time differential storage means is employed, this may preferably take the form of an electrical clock including opposed windings connected to respective of the groups. An alarm may be connected to the clock and operated by the same when the total cumulative time of a specific group reaches a critical limit.

In accordance with the invention, it is not necessary to limit the apparatus to only two groups of switches inasmuch as additional groups of switches may be employed according to the number of contestants which it is desired to accomodate. The switches of such further groups may be interconnected with each other and with the switches of the first and second groups.

As one preferred form of the invention, there is provided a casing which includes opposite and parallel faces on which the groups of switches are respectively mounted with the aforesaid operating members extending outwardly of the casing.

According to another feature of the invention, the operating members of each group may be physically arranged in a matrix having horizontal and vertical coordinates.

According to another embodiment of the invention, there may be provided physically separate supports for each group with means including cable connections being provided to interconnect the groups electrically.

In addition to the aforesaid features of the invention, the switches of each group may be connected in an electrical matrix including a plurality of electrically parallel coordinates, the coordinates of one group being differently arranged from the coordinates in the other group, continuous circuits being formed by switches arranged along any one of these coordinates.

The switches are preferably so interconnected that the forming of a continuous circuit in one group prevents the formation of a continuous circuit in the other group. Preferably, the aforesaid switches are doublepole double-throw switches although it will be clear that other types of switches may alternatively be employed within the scope of the invention.

The switches may advantageously be toggle type switches although push-button switches, magnetic switches, relays and other forms of devices suitable for forming and opening continuous circuits are suitable for use in accordance with the invention.

The invention will be more clearly understood from the following detailed description of some preferred embodiments as illustrated in the accompanying drawing;

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a perspective view of a game apparatus provided in accordance with a preferred embodiment o the invention; 7

FIG. 2 is a schematic diagram of the electric circuit employed in the apparatus illustrated in FIG. 1;

FIG. 3 illustrates a modification which can be employed in the electrical circuit of FIG. 2; and

FIG. 4 is a perspective view of a further embodiment of the invention.

DETAILED DESCRIPTION v As mentioned above, the apparatus of the invention comprises, generally, first and second groups of switches, the switches of each group being interconnected through the switches of the other group and being adapted for forming at least one continuous circuit in each group, there being associated with the aforesaid arrangement a power-source connected to each group and indicating means to indicate when a continuous circuit has been formed.

The aforesaid generalization will be better understood with reference to FIGS. 1 and 2 wherein is illustrated a specific and preferred embodiment of the invention.

In FIG. 1 appears a casing having opposite faces of which is illustrated the face 12 of rectangular shape. The casing furthermore has a top part 14 and a bottom (not shown) as well as a proximal end 16 and a distal end (not shown).

The discussion which next follows with respect to the face 12 applies equally to the opposite and paralled face which is not illustrated. More particularly, on the face 12 is mounted a plurality of switches 18, the operating members of which are visible and extend externally of the casing. These operating members appear as being arranged in a mechanical matrix and are distributed along horizontal and vertical coordinates, generally indicated respectively at 20 and 22. The coordinates may actually be inscribed on the face 12 or may alternatively be imaginary. Exactly the same mechanical arrangement of switches appears on the hidden face of the casing.

Thus use of the aforesaid switches will be made clear hereinafter. However, before proceeding to an explanation of the use of said switches, attention is directed to the fact that an off-on switch 24 is provided in end 16 to control the off-on condition of a power supply which is concealed within the casing 10. The power supply may take the form of dry cell batteries or the like and as alternatives, the use of a rechargeable battery may be considered as well as the use of an alternating current voltage supply which may be rectified or not according to conventional techniques.

It will be realized that the illustrated position of the off-on switch 24 is purely arbitrary and that any other desirable position for this switch may be selected.

On the top 14 of the casing 10 is illustrated a lamp 26. This lamp is intended to indicate when the power supply is effective under the control of the switch 24. Any other suitable arrangement for indicating the operability of the power supply may be employed and, for example, in one constructed embodiment of the invention, two lamps have been employed which alternately flash on and off thereby adding to the decor of the apparatus.

Furthermore positioned on the top 14 (although other locations are also possible) are lamps 28 and 30, a bell 32 and a clock 34. The purpose of the lamps 28 and is to indicate which of the contestants is momentarily or in some cases permanently victorious and each of these lamps is associated with one of the groups of switches on one of the faces of the casing as indicated hereinabove.

In the preferred embodiment of the invention, there is employed a clock mechanism 34 or an equivalent de-.

vice. This clock mechanism is intended to record or store the cumulative time advantage of one side over the other or in other words of one contestant over the other. Thus, for example, the clock 34 will run in one direction when the lamp 30 is lighted. As will be shown hereinafter, the lighting of lamps 28 and 30 is mutually exclusive and only one of these lamps can be lighted at a time. The clock 34 will algebraically total the amount of time which one lamp has advantageously accumulated over the other lamp and the arrangement is such (as will be shown hereinafter) that, when a critical time has been exceeded, the bell 32 will be sounded as an alarm to indicate that one of the contestants is victorious. It will be appreciated, however, that other alarms or indicating devices besides a bell may be employed within the scope of the invention and that, in fact, the bell and clock arrangement can beomitted in entirety from any particular embodiment of the invention. In such case, an indication will be simply given of the first continuous circuit which has been formed.

The electrical circuitry which is accommodated within the casing 10 is illustrated by the schematic diagram of FIG. 2 wherein are illustrated two electrical matrices of switches. These switches are interconnected within their respective groups and between the groups. They are connected in such a manner that it is only possible to form continuous circuits which are subject to being controlled by switches in the matrix of the other group.

To facilitate an understanding of the schematic diagram of FIG. 2, the switches of one matrix or of one group such as, for example, that associated with the face 12 of casing 10 are shown enclosed in boxes. The switches in this group include switches l8a-l8p. Switches 18a-d are connected along one horizontal coordinate of the electrical matrix; switches l8e-h are connected along a second horizontal coordinate; switches l8i-l are connected along the third horizontal coordinate; and switches 18m-p are connected along a fourth horizontal coordinate. The horizontal coordinates are the important coordinates for the switches l8a-p although these switches are also arranged along vertical coordinates; for example, switches 18a, e, i and m arearranged along a vertical coordinate.

In the second electrical matrix of switches, arranged on the hidden face of casing 10 in FIG. 1, are included switches 36a-36p. Switches 36a-d are arranged along one vertical coordinate; switches 36e-h are arranged along a second vertical coordinate; switches 36i-l are arranged along a third vertical coordinate; and switches 36m-p are arranged along a fourth vertical coordinate. Switches 36a-d, for example, are also arranged along a horizontal coordinate, but it is the vertical coordinate which is important as will subsequently appear.

As has been mentioned hereinabove, the switches of one matrix or group are connected with each other but through the switches of the other matrix or group. A typical arrangement of one of the resulting switch pairs is next given with respect to switches 18a and 36a.

Switches 18a comprises contacts 38, 40, 42, 44, 46 and 48. The switch blades are indicated at 50 and 52 and these switch blades have a common operating member 54 so that the switch style employed in the illustrated circuit is of the double-pole double-throw type.

Switch 36a includes contacts 56, 58, 60, 62, 64 and 66. This switch includes switch blades 68 and 70 having a common operating member 72 so that switch 36a is also of the double-pole double-throw type. As a matter of fact, it will be noted all of the switches employed in the two illustrated matrices are of the double-pole double-throw type.

Sources of voltage or current are respectively supplied to switches 18a and 36a via lines 74 and 76, the electrical power connected to these lines being indicated in greater detail hereinafter. Current or voltage is typically transmitted from switch 18a via line 78 along the associated horizontal coordinate and is typically transmitted from switch 36a via line 80 along the associated vertical coordinate. This transmission of electrical power is, however, under the control of the operating members 54 and 72.

To get the desired transmission of electrical power under the desired condition, contact 38 is connected via line 82 to contact 66. Contact 40 is connected via line 84 to contact 56. Contact 46 is connected via line 86 to contact 58 and contact 48 is connected via line 88 to contact 64.

When operating member 54 is in its upper position, switch blade 50 connects contact 42 to contact 38 and thus power is supplied via line 82 to contact 66 of the other switch. Under these conditions, if the operating member 72 isin its lower position, blade 70 will connect contact 66 to contact 62 and thus to line 80. At the same time, blade 52 will connect contact 40 to contact 44 and thus if power is supplied from switch 36a via line 84 to contact 40, power will'be transmitted along line 78 to switch 18b.

On the other hand, if the operating member 54 is in its lowermost position, blade 50 will connect contact 42 to contact 46 and thence via line 86 to contact 58. At the same time blade 52 will connect contacts 44 and 48 so that, if power appears at contact 64, this power will be transmitted via line 78.

As mentioned hereinabove, switch 36a includes operating member 72 which controls blades 68 and'70. Thus, power which appears on line 76 may be transmitted under the control of an operator to contacts 56 and 64 and then, depending upon whether the operating members 54 is in upper or lower position, power can be transmitted along line 78.

Analysis of the above arrangement will show that if operating members 54 and,72 are both up, power will be transmitted'along line 78 or in other words, along the horizontal coordinate to the next successive switch which in this case is switch 18b. Similarly, if both operating member 54 and 72 are down, power will likewise be transmitted along line 78 to the next successive switch (switch 18b) in the horizontal coordinate.

However, if one of the operating members 54 or 72 is up and the other is down or vice versa, power will instead be transmitted from the switch 36a upwardly along the vertical coordinate which in this case is constituded by the line 80.

lt is therefore possible in accordance with the schematic arrangement illustrated in FIG. 2 to generate a continuous circuit along one of the horizontal coordinates or along one of the vertical coordinates. Which matrix generates a continuous circuit will be under the control of the respective operating members of the various switches and these operating members will in turn be under the control of the respective contestants. Each contestant will operate his own matrix of switches without knowledge of the condition or state of operation of the switches of the other contestant. Continuous operation of the two matrices of switches will be necessary before one of the matrices can generate a continuous circuit.

In connection with the aforesaid matrices, there is provided a power source indicated generally at 90. This power source is illustrative of the many types of power sources which may be employed. The power source is connected by a bus 92 to the first switches in the respective horizontal and vertical coordinates. Thus, for example, bus 92 is connected via line 74 to contact 42 of switch 18a and is furthermore, for example, connected via line 94 to power input terminal or contact 96 of switch 36d.

' The outputs of the various vertical and horizontal coordinates are constituted by lines 80, 98, 100 and 102 for the vertical coordinates and by lines 104, 106, 108 and 110 for the horizontal coordinates. Lines 80, 98, 100 and 102 are connected to bus 112 whereas lines 104,106, 108 and 110 are connected to bus 114. These busses make closed circuits with power source 90 through lamps 28 and 30 mentioned hereinabove with respect to FIG. 1. Some other elements are included in this closed circuit as will be indicated in greater detail hereinafter. It will now be noted that, when any single horizontal or vertical coordinate becomes a closed continuous circuit due to the operation of the aforementioned switches, the corresponding lamps 28 or 30 will be lighted thereby indicating that the associated contestant has been victorious.

As has also been noted above with respect to FIG. 1, a total time accumulator is provided in the form of a clock 34. This clock includes windings 116 and 118 to which currents passing through the respective lamps 30 and 28 will flow. windings 116and 118 are effective to operate a motor mechanism (not shown) to drive pointer 120 in either of two opposite rotary directions indicated generally by arrow 122. Thus, when winding 1 16 is operated the pointer 120 will rotate in one direction whereas when winding 1 18 isenergized the pointer 120 will rotate in the opposite direction. The effect will be the algebraic totaling of the time during which lamps 28 nd 30 are respectively lighted and the pointer 120- will indicate the total accumulative time differential between the times of formation of continuous circuits in the respective groups or matrices.

When a critical accumulative time value has been achieved, the pointer 120 will arrive at either contact 124 or 126. This will have the efiect of providing a closed circuit between bell 32 (indicated hereinabove with respect to FIG. 1) and a power source 128. Thus, an alarm will be sounded by bell 32 indicating that one of the contestants has accumulated a total time value or closed circuits within his associated matrix and has therefore won the game."

It will be readily appreciated that the indicated rules of the game are illustrative only and that other rules may be provided or employed. Thus, for example, it may be desirous to avoid having continuous circuits in acompetitors matrix, in which event the sounding of the bell or alarm will indicate a loser." It will also be noted that, while a separate power source 128 has been indicated for the bell 32, this is not at all necessary 1 will be lighted when the switch 24 is closed and the power source 90 is effective to operate the aforesaid matrices.

It will be readily appreciated from the aforementioned discussion of FIG. 2 that it is possible to omit the lamps 28 and 30 and depend solely upon operation of the time storage mechanism or clock 34 or that alternativcly it is possible to omit clock 34 and retain the lamps 28 and 30. Similarly, bell 32 may be employed or not according to the specific design which is desired. Additionally, other deviced may be used in substitution for the aforesaid lamps, clock and bell as desired.

In accordance with the embodiment of the invention which has been discussed relative to FIGS. 1 and 2, only two mechanical matrices of switches connected in respective electrical matrices have been indicated. It is not, however, necessary to limit the game apparatus to this number of groups or matrices, nor is it necessary to use the specific switches in the specific arrangements which have been shown. FIG. 3 illustrates by way of example possible substitute switches which may be employed instead of the switches 18 and 36 of FIG. 2. In FIG. 3 are shown switches 140 and 142. Switch 140 includes contacts 144, 146, 148 and 150 as well as contacts 152 and 154. Switch blades 156 and 158 are provided, these being operable independently of one another so that an entirely different result is achieved.

Similarly, switch 142 includes contacts 160, 162, 164, 166, 168 and 170 with which are associated individually operated switch blades 172 and 174.

Power is supplied to switch 140 via line 176 and to switch 142 via line 178. Power is derived from switch 140 via line 180 and from switch 170 via line 182.

The connection between contact 144 and contact 170 is via line 184 and between contacts 146 and 160 via line 186. Connection between contacts 152 and 162 is provided by line 188 and line 190 connects contacts 154 and 166.

It will be obvious that a switch arrangement of the above type can be employed by duplication to form two separate matrices or groups of switches which operate generally in the manner described with respect to FIG. 2 but which requires two separate controls for each switch.

In addition to the aforegoing variation of the invention, it is also possible to employ magnetic switches, relays, reed switches, push-button switches and the like while still operating within the scope of the invention.

FIG. 4 illustrates an arrangement by which the apparatus of the invention is modified to provide for a greater number of competitors. Herein is illustrated a central unit 200 connected by cables 202, 204, 206 and 208 to switch. panels 210, 212, 214 and 216.

Reference to panel 214 will show that there is provided a matrix of switches 218 which is duplicated on each of the other panels.

The aforesaid electrical connections such as, for example, illustrated in FIG. 2 may be provided by means of the cables 202, 204, 206 and 208 with the necessary circuitry being incorporated within the unit 200.

On top of unit 200 are provided lamp 220, 222, 224 and 226, these being effective to indicate when one of the competitors has been victorious.

In this arrangement, it is possible to employ the time totalizing or storage unit 228, as has been mentioned hereinabove, and it is further possible to arrange the circuit such that the competitors may operate as part.-

ners cooperating with one another against the competitors forming the other partnership.

From what has been stated hereinabove, it will now appear that the invention provides an apparatus comprising at least first and second groups of switches, the switches of each group being interconnected through the switches of the'other group and being adapted for forming at least one continuous circuit in each group, a power source being connected to each group and indicating means being provided to indicate when a continuous circuit has been formed.

As has been noted, the switches are connected in respective matrices and although these have been generally indicated as being horizontal or vertical, it will be readily appreciated that the attitude of the matrices is relatively unimportant and is not limitative with respect to the invention. It should additionally be noted that these matrices need not be constituted by coordinates which are rectilinear or of any other particular shape.

Similarly, it should be noted that the invention is not limited to arrangements requiring that the switches of the different matrices have any generalized relationship to one another in order to achieve the transmission of power to the next sequential switch in the respective or associated coordinate since this may be arbitrarily chosenwhile embodying the features of the invention. In other words, it is entirely possible that different switch pairs may respond to different arrangement for the transmission of power.

There will now be obvious to those skilled in the art many modifications and variations of the construction set forth hereinabove. These modifications and variations will not depart from the scope of the invention if defined by the following claims:

What is claimed is:

1. Apparatus comprising first and second groups of switches, the switches of each group being interconnected through the switches of the other group and being adapted for forming at least one continuous circuit in each group, a power source connected to each group, and indicating means to indicate when a continuous circuit is formed, each switch including an operating member, the operating members of each group being physically juxtaposed and spaced from the operating members of the other, group, said indicating means including means for storing the total cumulative time differential between the times of formation of continuous circuits in the respective groups.

2. Apparatus as claimed in claim 1 wherein said indicating means includes an indicator for each group.

3. Apparatus as claimed in claim 2 wherein the indicators are lamps.

4. Apparatus as claimed in claim 1 wherein the latter said means includes an electric clock including opposed windings connected to respective of said groups.

5. Apparatus as claimed in claim 1 including an alarm connected to the latter said means and operable when said total cumulative time reaches a critical limit.

6. Apparatus as claimed in claim 1 comprising further groups of switches coupled to said indicating means.

7. Apparatus as claimed in claim 6 wherein the switches of said further groups are interconnected with each other and between said further groups and with the switches of said first and second groups.

8. Apparatus as claimed in claim 7 comprising physically separate supports for each group and means including cable connections to interconnect the groups electrically.

9. Apparatus as claimed in claim 1 comprising a casing including opposite faces on which said groups of switches are respectively mounted with the operating members extending outwardly of said casing.

10. Apparatus as claimed in claim 9 wherein the operating members of each group are physically arranged in a matrix.

11. Apparatus as claimed in claim 1 comprising physically separate supports for each group and means including cable connections to interconnect the groups electrically.

12. Apparatus as claimed in claim 1 wherein the switches of each group are connected in an electrical matrix including a plurality of electrically parallel coordinates, the coordinates in one group being differently arranged from the coordinates in the other group, said continuous circuit being formed by the switches arranged along any one of said coordinates.

13. Apparatus as claimed in claim 12 wherein the switches are so interconnected that the forming of a continuous circuit in one group prevents the formation of a continuous circuit in the group.

14. Apparatus as claimed in claim 1 wherein the switches are so interconnected that the forming of a continuous circuit in one group prevents the formation of a continuous circuit in the other group.

15. Apparatus as claimed in claim 1 wherein the switches are double-pole double-throw switches.

16. Apparatus as claimed in claim 15 wherein the switches are toggle switches. 

1. Apparatus comprising first and second groups of switches, the switches of each group being interconnected through the switches of the other group and being adapted for forming at least one continuous circuit in each group, a power source connected to each group, and indicating means to indicate when a continuous circuit is formed, each switch including an operating member, the operating members of each group being physically juxtaposed and spaced from the operating members of the other group, said indicating means including means for storing the total cumulative time differential between the times of formation of continuous circuits in the respective groups.
 2. Apparatus as claimed in claim 1 wherein said indicating means includes an indicator for each group.
 3. Apparatus as claimed in claim 2 wherein the indicators are lamps.
 4. Apparatus as claimed in claim 1 wherein the latter said means includes an electric clock including opposed windings connected to respective of said groups.
 5. Apparatus as claimed in claim 1 including an alarm connected to the latter said means and operable when said total cumulative time reaches a critical limit.
 6. Apparatus as claimed in claim 1 comprising further groups of switches coupled to said indicating means.
 7. AppaRatus as claimed in claim 6 wherein the switches of said further groups are interconnected with each other and between said further groups and with the switches of said first and second groups.
 8. Apparatus as claimed in claim 7 comprising physically separate supports for each group and means including cable connections to interconnect the groups electrically.
 9. Apparatus as claimed in claim 1 comprising a casing including opposite faces on which said groups of switches are respectively mounted with the operating members extending outwardly of said casing.
 10. Apparatus as claimed in claim 9 wherein the operating members of each group are physically arranged in a matrix.
 11. Apparatus as claimed in claim 1 comprising physically separate supports for each group and means including cable connections to interconnect the groups electrically.
 12. Apparatus as claimed in claim 1 wherein the switches of each group are connected in an electrical matrix including a plurality of electrically parallel coordinates, the coordinates in one group being differently arranged from the coordinates in the other group, said continuous circuit being formed by the switches arranged along any one of said coordinates.
 13. Apparatus as claimed in claim 12 wherein the switches are so interconnected that the forming of a continuous circuit in one group prevents the formation of a continuous circuit in the group.
 14. Apparatus as claimed in claim 1 wherein the switches are so interconnected that the forming of a continuous circuit in one group prevents the formation of a continuous circuit in the other group.
 15. Apparatus as claimed in claim 1 wherein the switches are double-pole double-throw switches.
 16. Apparatus as claimed in claim 15 wherein the switches are toggle switches. 